Operation analysis method for natural gas plant

Abstract

An operation analysis method for a natural gas plant includes: acquiring production amount data of a product per unit time and operation data of a plurality of controlled devices forming the natural gas plant in association with each other along a time series; determining whether or not a controlled device that violates the operation constraint is present at the time point of acquisition of the production amount data when the production amount data is less than the reference production amount, and performing data processing of associating an item subjected to the operation constraint to the production amount data; and determining, for each of the items subjected to the operation constraints, a length of a period with the production reduction in accordance with a magnitude of the production reduction amount.

The invention claimed is: 
     
       1. An operation analysis method for a natural gas plant, the natural gas plant is configured to produce a product from natural gas, the operation analysis method comprising:
 acquiring production amount data per unit time of the product and operation data of a plurality of controlled devices, which form the natural gas plant and each of the plurality of controlled device is subjected to operation control within a preset range of an operation constraints, for determination of whether or not each of the controlled devices violates the operation constraint, wherein the production amount data and the operation data are in association with a time series; 
 with use of a computer, comparing a preset reference production amount per unit time and the production amount data, wherein a controlled device of the plurality of controlled devices that violates the operation constraint is present at a time point of acquisition of the production amount data less than the preset reference production amount, and performing data processing of associating an item subjected to the operation constraint related to the controlled device with the production amount data; and 
 determining a production reduction amount that is a difference between production amount data associated with the item subjected to the operation constraint and the preset reference production amount, and determining, for each of the items subjected to the operation constraints, a length of a period with the production amount data being less than the preset reference production amount in accordance with a magnitude of the production reduction amount. 
 
     
     
       2. The operation analysis method for a natural gas plant according to  claim 1 , further comprising visualizing a correspondence between the length of the period with the production amount data being less than the preset reference production amount and the magnitude of the production reduction amount in a graph for the item subjected to the operation constraint. 
     
     
       3. The operation analysis method for a natural gas plant according to  claim 1 , wherein, in the determining the length of the period with the production amount data being less than the preset reference production amount, when a plurality of items subjected to a plurality of operation constraints are associated with the production amount data, based on priority set in advance for the items subjected to the operation constraints, an item of the plurality of items subjected to an operation constraint of the plurality of operation constraints that has a highest priority is included in the period in which the production amount data is less than the preset reference production amount. 
     
     
       4. The operation analysis method for a natural gas plant according to  claim 3 , wherein, with regard to the item subjected to the operation constraint having the highest priority, for the production amount data included in the period with the production amount data being less than the preset reference production amount, a period with the production amount data for a remainder of the operation constraints being less than the preset reference production amount is repeatedly calculated. 
     
     
       5. The operation analysis method for a natural gas plant according to  claim 1 , wherein the natural gas plant is a liquefied natural gas plant for producing liquefied natural gas as a product from natural gas, or a natural gas processing plant for separating and collecting at least one of liquefied petroleum gas (LPG), a heavy component, or a light component as a product from natural gas. 
     
     
       6. The operation analysis method for a natural gas plant according to  claim 1 , wherein combinations of the controlled devices and the respective items subjected to operation constraints include at least one of the combinations selected from a combination group consisting of:
 (i) when the natural gas plant includes a compressor for precooling refrigerant for the natural gas, the controlled device is the precooling compressor and the item subjected to operation constraint is a discharge pressure upper limit value of the precooling compressor; 
 (ii) when the natural gas plant includes a compressor for liquefying refrigerant for the natural gas, the controlled device is the liquefying compressor and the item subjected to operation constraint is a drive force upper limit value of the liquefying compressor; 
 (iii) when the natural gas plant liquefies the natural gas with use of the liquefying refrigerant, the controlled device is a flow rate adjusting unit for the liquefying refrigerant and the item subjected to operation constraint is a flow rate upper limit of the liquefying refrigerant; 
 (iv) when the natural gas plant includes an acid gas removal unit configured to remove acid gas included in the natural gas by bringing the natural gas and an absorption liquid for acid gas into contact with each other, the controlled device is the acid gas removal unit and the item subjected to operation constraint is an upper limit value of a supply flow rate of the absorption liquid to the acid gas removal unit; and 
 (v) when the natural gas plant includes an acid gas removal unit configured to remove acid gas included in the natural gas by bringing the natural gas and an absorption liquid for acid gas into contact with each other, the controlled device is the acid gas removal unit and the item subjected to operation constraint is an acid gas content upper limit of the natural gas having been processed by the acid gas removal unit.